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Safe Viewing of Rare Transit of Mercury

Event Details

November 11, 2019
7:30 am-1:00 pm


UMass Amherst Campus

Handicap access available
Free admission

On Monday, Nov. 11, the planet Mercury will pass in front of the sun, an event that will not be visible in North America again until 2049.

Weather permitting, UMass astronomers invite the public to view this transit of Mercury. Telescopes will be set up to safely observe Mercury's progress between 7:36 a.m. to 1:04 p.m., while astronomers explain what’s happening. During this rare event, the planet will appear as a tiny black dot crossing the face of the sun for several hours.

Mercury is so small that a transit can only be seen through a telescope, but to prevent serious eye damage it is extremely important to view it only using properly designed filters. There is no time during a transit when it is safe to look at the sun directly, and Mercury is too small to be seen through eclipse glasses.

Mercury orbits the Sun every 88 days, but it is only properly aligned with Earth about a dozen times each century for a transit to be seen, the astronomer says. In addition to the rarity of the alignments making it difficult to witness, one must also be on the daytime side of Earth to see it. The entire 2019 transit is visible from the East Coast of the United States this year, but the next two transits in 2032 and 2039 will occur at night in North America, he adds.

The slight dimming of the light from a star during a transit is of interest to astronomers because it is the method that has been used to detect exoplanets orbiting other stars. Mercury, the planet closest to the sun, is about two-fifths the diameter of Earth. The transit will provide a glimpse of just how large stars are, compared to planets.



The UMass Amherst Sunwheel is located south of McGuirk Alumni Stadium, just off Rocky Hill Road (Amity St.) about one-quarter mile south of University Drive.

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